Oil cooler bypass valves are used in conjunction with engines, transmissions, power steering systems, and hydraulic systems. They are designed to provide a flow path by which oil passing to the valve from the oil source is returned without passing through a heat exchanger during warm-up periods.
Typical transmission bypass valves have several connecting joints and complicated return features which increases costs and the likelihood of failures caused by leaks. In most prior art systems, the valve member is an integral part of a thermally responsive element which expands to cause the valve member to engage the valve seat. Once seated such a valve member is susceptible to at least two malfunctions. It is impossible to unseat the valve member to relieve excessive system pressures which may occur if the valve ports are improperly connected to the cooler or in the event the oil line is damaged or blocked or the cooler itself has become inoperable. Secondly, the components of the bypass valve are often damaged when the thermally responsive element continues to expand, which sometimes occurs when the cooler is overloaded and the oil heats excessively. Such damage can include cracking of the valve member mounting, or internal failure of the valve components. In either case the bypass valve is unfit for further service.